Treating olefin polymers



Patent ed Dec, 11, 1945 TREATING QLEFLIN POLYMERS Bernard H. Shoemaker,Hammond, Ind., and Edmond L. dOuville, Chicago, 111., assignors toStandard Oil Company, Chicago, 111., a corporation of Indiana NoDrawing. Application March so, 1942,

Serial No. 436,769

' 13 Claims.

This invention relates to high molecular weight organic substances ofthe character of plastics, rubber and elastomers or polymeric compoundshaving elastic properties. More particularly, the invention relates tohigh molecular weight linear olefin polymers and to a process ofhardening or vulcanizing olefin polymers especially isoolefin polymers,such as the polymers of isobutylene.

One object of the invention is to convert heavy d isoolefin polymersandlinear mono-olefin polymersgenerally into. a form vulcanizable bysulfur. Another object of the invention is to desaturate isdbutylenepolymers or resins knownas viscoresins by a rapid, simple and economicalprocess.

It is known that when liquid isoolefins, such as liquid is'obutylene,are subjected to the action of a, Friedel-Crafts type catalyst,preferably at low temperature, there will result polymers of highmolecular weight, generally ranging from 1000 to 200,000 or even higher.The molecular weights of these very heavy hydrocarbons are mostconmethod. The lower the temperature of the polymerization, the highenthe molecular weight of the product.

obtained at temperatures of the order of '-100 F. The low temperaturefor the reaction is conveniently obtained by direct cooling, using aninert diluent which is also a refrigerant, that is, one which boils atthe desired reaction tempera- The very high molecular weight. materials,of the order of 50,000 to 150,000, are

adding about 1 to 20% of butadieneto the isobutylene. Unsaturatedhalogen compounds may also be co-polymerized with the isoolefins, suchas methallyl chloride.

The reaction, is normally quite rapid, being complete within 5 minutesto 1 or 2 hours and it may be halted at any point desired by adding aquenching agent which deactivates the catalyst. The alcohols, such asethyl and isopropyl alcohols, aqueous ethyl ether, ammonia, causticalkali solutions, and various similar substances of 10w freezing pointmay be conveniently employed veniently determined by the Staudingerviscosity face is provided to remove the heat of the polymerizationreaction sufflciently rapidly.-

By Friedel-Crafts catalysts we mean to include those active metalhalides hydrolyzable by water to produce halogen acid. Aluminum chlorideand aluminum bromide are examples. Boron fluoride, boron chloride,ferric chloride, tin tetrachloride and titanium tetrachloride may alsobe mentioned. These may be used alone or mixed The polymerization of theisoolefin may be carried out with the pure isoolefin alone or withmixtures of isooleflns with one another, with inert diluents or withother unsaturated hydrocarbons which have the faculty of co-polymerizingwith theisooleflns. One example of the latter reactionis theco-polymerization of isobutylene with a small amount or butadienebrought about by as quenching agents, 7

The product of the reaction is generally a viscous or semi-solidplastic, sticky mass, difficult to handle unless retained in solution.Inert solvents such as liquid butane, hexane, naptha, etc. may be addedbefore, during or after polymerizationeto facilitate handling theproduct. After washing, the polymer product may be separated from thesolution by evaporation or by precipitation with other solvents such asacetone which has the property of throwing down the polymer of highmolecular weight. The solvent-free polymer product obtained in this waymaybe a sticky, viscous, plastic material with a slight tendency to flowor it may be a tough, rubbery solid, depending on molecular weight. Forthe present invention, we prefer to employ polymers of higher molecularweight, of the order of 50,000 to 100,000

or higher. .However, our dehydrogenation-vul- 'and given other usefulproperties by treatment in accordance with our invention. Thus,sulfurcontaining materials suitable as addition agents for lubricatingoils may be obtained from the soft polymers.

An important characteristic of the isoolefin polymers, particularly theisobutylene polymers obtained in the foregoing manner, is theirchemiwhich is known to be readily replaceable, It provides the secondaryhydrogen in a position of unreactivity where stearic hindranceapparently prevents its being replaced in the manner one would normallyexpect. As a consequence, the isobutylene polymers resist attack bychemical agents such as sulfuric acid and they are difficult tohalogenate, especially at low temperatures.

We have now discovered that these polymers may be readily attacked byhalogens in the presenceof substantial quantities of active metalhalides or Friedel-Crafts catalyst, particularly aluminum chloride.reaction may be carried out at ordinary temperatures or withrefrigeration. None of the ordinary halogenating catalyst such as iodineor actinic light are needed. Furthermore, we have discovered that thehalogen does not remain in Under these conditions the' temperature. Atthese low temperatures, the polymer would normally be unattacked bychlorine, but in the presence of the aluminum chloride thehalodehydrogenation reaction can be carried out smoothly at quite lowtemperatures, as low as 0 F. and lower.

It is desirable to employa solvent for the hydrocarbon polymer in thehalodehydrogenation treatment. For this purpose we may use hydrocarbonsolvents such as butane, hexane, straight run petroleum napthas, etc. orCS2, carbon tetrachloride, methylchloride, methylene chloride and inerthalogenated solvents generally.

The following examples show the character of the halodehydrogenationreaction when applied to isobutylene polymers having a molecular weightof about 100,000. To a carbon tetrachloride soluthe hydrocarbon but isremoved as halogen acid.

For example, when isobutylene polymers are treated with chlorine in thepresence of substantial amounts of aluminum chloride, the chlorine maybe mostly all accounted for by the HCl 'gas evolved in the reaction. Asthe reaction proceeds, the polymers form a dark colored complex withaluminum chloride. At the end of the reaction this complex is decomposedwith water, alcohol,

alkalies, etc., and the hydrocarbon product is recovered as a lightcolored product, the dark color of the complex being discharged when thecomplex is decomposed by the water.

The reaction product obtained in this way is an unsaturated material,substantially free of halogen, having approximately the same physicalcharacteristics as the viscoresin treated. The degree of unsaturationdepends on the amount of chlorine used in the reaction and may beregulated at will. The chemical characteristics resulting from theunsaturation render the product susceptible to vulcanization by theaction of sulfur, sulfur chloride, or other sulfur compounds,

strong elastic products being obtained. If the tion containing grams ofthe polymer there was added 1 gram of aluminum chloride dissolved inC014. The addition of 15 grams of bromine produced no reaction even whenheated to 160 F. On adding more aluminum chloride, however, a vigorousreaction took place with the evolution of HBr. Ten (10) grams ofaluminum chloride were added before the reaction was complete,Substantially all of the bromine was recovered as I-IBr. Alcohol wasadded to deactivate the aluminum chloride and decompose the complex. Theproduct was precipitated from the solution with acetone with a yield of20 grams.

In another experiment 16.5 grams of A1013 were added to a hexanesolution of 43 grams of isobutylene polymer. To the mixture there wasthen added 10 grams of bromine and after two hours, alcohol was addedand the hexane was removed by heating on the steam bath. The product waswashed with hot water and acetone and then vulcanized, one sample fortwohours at 325 F. and another sample for four hours at 225 F., thefollowing vulcanization mixture being em- It will be observed that thereaction of halo-' I gens under these conditions is not a truehalogenation but rather a dehydrogenation by means of halogen. To thisreaction we apply the term halodehydrogenation. The part played by thealuminum chloride in this reaction is not entirely understood but it isbelieved that the aluminum chloride may rearrange the structure of thehydrocarbon polymer in such a way as to activate certain of the hydrogenatoms.

It is otherwise diflicult to account structurally for the removal ofhydrogen molecules in which no two adjacent carbon atoms eachcontainreplaceable hydrogen.

In order to produce the desired reaction product,it is important thatthe isoolefin polymer be treated in such a manner that little or noreduction in molecular weight occur in the process inasmuch aS- thedesired, physical properties,

- strength, elasticity, resiliency, etc. are only obtainable incompounds of high molecular weight. Accordingly, it is undesirable toconduct the reaction at elevated temperatures tending to bring about areductionin molecular weight of the isoolefin polymers. The efiect oftemperature'is es-- pecially marked in the presence of chemicalreagents, HCl, aluminum chloride, chlorine, etc.

- Accordingly, it is desirable to keep the temperature below about 175F. and preferably below- 125 F. A satisfactory range is 32 F. to room.'to the original polymer in strength and elasticity.

ployed:

. Parts Polymer 38 Sulfur 2 ZnO 3 Stearic acid 7 v 2 Tuads(tetramethylthiuram disulflde) 1 Mercaptobenzothiazole 1 The vulcanizedproducts were definitely superior In another operation the polymer of100,000 molecular weight was dissolved in carbon tetrachloride. Aluminumchloride equivalent to 40% of the polymer was dispersed in the solution.Bromine equivalent to 25% by weight of the viscoresin was dissolved incarbon tetrachloride and added gradually, drop by drop, over a period ofone hour. The reaction temperature was held at 32 F. All the brominereacted and HBr was evolved. After two hours the temperature was allowedto rise to F. and then 95% ethyl alcohol was added to quench thealuminum chloride. The product was hydrolyzed and washed six times withwater while still in the carbon tetrachloride solution. Carbontetrachloride was then mostly removed by a stream of nitrogen at 100 F.The

- concentrated solution was poured into acetone to precipitate theproductwhich was finally .washed with acetone to remove most of thecarbon tetrachloride. The yield was approximately based on thehydrocarbon polymer charged. When vulcanized in the manner describedabove, using sulfur and accelerators, atough, strong, elastic materialwas obtained.

. the weight of the hydrocarbon treated.

' Although the experiments just described were conducted with theisolated p lymer from the mono-olefin polymerization reaction, wecontemplate carrying out the halodehydrogenation step of the process indirect conjunction with the polymerization step in the following manner:The liquid isobutylene or other isoolefin hydrocarbon is polymerized bythe addition of a solution of aluminum chloride in a chlorinatedsolvent, for example, ethylene dichloride. When the polymerization iscomplete at the low temperature, e. g., to -100 F., there is added thedesired amount molecular weight above 1000 resulting from thevpolymerization of an olefin hydrocarbon with a Frledel-Crafts catalystat a temperature below 0 F. comprising subjecting the said substantially'of halogen, for example, fluorine, chlorine or bro mine. More aluminumchloride or bromide may be added at the same time if desired. Themixture may be held at the low temperature ofthe polymerization reactionfor a period of time to permit the halodehydrogenation reaction to go tocompletion or the'mixture may be allowed to warm 7 up and remain at 32F. or at room temperature to permit completion of thehalodehydrogenation reaction before quenching the reaction with water,alcohol, or other quenching reagent.

Operating in this manner, the same catalystemployed for thepolymerization of the isoolefin mayserve also in the halodehydrogenationreaction. Likewise, the intermediate steps of isolating the hydrocarbonpolymer from the polymerization reaction are rendered unnecessary. Wemay also use a different catalyst for the two steps of the reaction whenoperating in this way. Thus, we may carry out the polymerization withBF: and then, leaving the BF: in the reaction mixture, we may addaluminum chloride or other active metal halide for thehalodehydrogenation reaction.

The amount of Friedel-Crafts catalyst required for the polymerization isrelatively small, generally of the order of /2% to 5% of the weight ofthe isoolefin present. Larger amounts may be used, however, if desired,especially in the case of the combined operation where the catalyst isretained in the mixture through the halodehydrogenation step of theprocess. The amount of Friedel-Crafts catalyst employed in thehalodehydro enation reaction is generally about 20 to 50% gf T e amountrequired depends to some extent on the amount of halogen to be added. IngeneraLabout to of aluminum chloride is suflicient 'for vulcanizationpurposes but for certain special uses, where less halogen is employed,the amount of Friedel-Crafts catalyst may be reduced to 10 or 15% in thehalodehydrogenation step.

The amount of halogen employed will vary with the degree of unsaturationdesired. Where chlorine is employed, the amount may be from 5% to of theweight of the resin, or more.

ed equal to 1 to 3 times the weight of the resin. The same holds truefor other halogens. The halodehydrogenated isoolefin Polymer may beemployed for other purposes besides vulcanization. Lower molecularweight polymers, for

example, may be subjected to mild sulfurization with elemental sulfur orwith one of the sulfur to lubricating oils may be prepared by treatment.with phosphorus chlorides or phosphorus sulfides,

for example, phosphorus pentas lfi e, r by the a direct addition ofelemental phosphorus. The de- Thus, ,in some cases an amount of chlorinemay be addsaturated polymer to the action of a halogen in the presenceof at least 10% by weight of a Friedel-Cratts catalyst at about 32 to175 F. whereby substantially all the added halogen is eliminated ashalogen acid, then separating the catalyst from the resultingunsaturated polymer product.

2. The process of claim 1 wherein the treatment with halogen isconducted in the presence of 10% to 50% of aluminum chloride, based onthe weight of the hydrocarbon polymer employed.

3. The process of claim 1 wherein the treatment with halogen is carriedout in the presence of 30-40% of aluminum chloride, based on the weightof the hydrocarbon polymer employed.

4. A vulcanizable rubber-like hydrocarbon polymer of high molecularweight prepared by the halodehydrogenation of a-substantiall saturatedlinear polymer ofisobutylene having a molecular weight upwards of 50,000wherein the said polymer-is treated with-at least 5% byweight of halogenin the presence of at least 10% of a Friedel-Crafts catalyst, thenseparated from the catalyst by washing.

5. The product of claim 4 wherein the Friedel- Crafts cataylst isaluminum chloride.

6. The product of claim 4 wherein the Friedel- Crafts catalyst isaluminum bromide.

7. The process of producing unsaturated high molecular weight resinswhich comprises polymerizing an isoolefin hydrocarbon at a temperaturebelow about 0 F. in the presence of a Friedel-Crafts catalyst to give apolymer with a molecular weight above 1000, then without separating thepolymer from the reaction mixture, subjecting said polymer tohalodehydrogenation by adding to said reaction mixture at least 10% ofanhydrous aluminum chloride and then at least 5% of a halogen,maintaining the temperaated hydrocarbon solvent is employed in saidhalodehydrogenation reaction.

9. The process of claim 7 wherein polymerizae tion is effected in thepresence of anhydrous aluminum chloride. v

10. The process of claim 7 wherein polymerization isefiected in thepresence of boron fluoride.

11. The process of producing a vulcanizable hydrocarbon resin whichcomprises polymerizing liquid isobutylene with boron fluoride catalystat a low temperature below 0 F., thereby producing a linear: polymerwith amolecular weight above 1000, adding at least 10% by weight ofanhydrous aluminum chloride to the polymer product and boron fluoridecatalyst and passing into the mixture at least 10% by weight of chlorinewhile holding the reaction mixture below about 32 F. untilhalodehydrogenation is substantially complete.

12. The process of desaturating' substantially saturated, linearisobutylene polymer resins having molecular weights above about 1000whereby saidresins are rendered more reactive and vuleanizable whichcomprises treating said resins with at least 5% of chlorine in thepresence of 10 to'50% of aluminum chloride at a temperature 01 about .32to 175 F. whereby hydrochloric acid is eliminated and substantiallynochloride remains in combination with said resin and'thereafterseparating the desired desaturated resin from the aluminum-chloride.

13. The process of making arubber-iike material from a substantiallysaturated linear polymer havin'g a molecular weight above about. I10,000" resultingv from the polymerization ofan 15 6 10 per cent byweight of aluminum chloride at 'about 0 to 175 F. whereby substantiallyall the added halogen is eliminated as halogen acid and an unsaturatedpolymer product is produced, separatingv the unsaturated polymer productfrom the reaction mixture and vulcanizing the product to produce therubber-like material in the desired form.

BERNARD H. SHOEMAKER. EDMOND L.- DOUVILLE..

